1. Field of the Invention
The present invention relates to a backlight assembly, and more particularly, to a backlight assembly of a liquid crystal display capable of enhancing screen brightness distribution uniformity as well as screen quality.
2. Description of the Related Art
Various types of flat panel displays which are considerably lighter and less bulky than Cathode Ray Tubes (CRTs) have recently been developed. Such flat panel displays include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an electro-luminescence (EL) display and so forth. In the field of flat panel displays, a great deal of research has been conducted into enhancing display quality and implementing a large screen.
Among the flat panel displays, the LCD is a non-emissive display using a light source such as a lamp to represent an image. The LCD has advantages of small size, light weight, and low power consumption, and uses electrical and optical properties of a liquid crystal injected into an LCD panel to display information.
The LCD, unlike the CRT, needs a separate device for radiating light onto the LCD panel, i.e., a backlight module, because the liquid crystal material injected between a Thin Film Transistor (TFT) substrate and a color filter substrate is not self-emissive but rather non-emissive, that is, the liquid crystal material merely adjusts an amount of externally incoming light to display it on a screen.
According to the conventional art, an LCD backlight module having high energy efficiency and a long lifetime is disclosed in Korean Patent Publication No. 2005-105823 entitled “Backlight Module Using LED for LCD.”
FIG. 1 is a disassembled perspective view of an LCD backlight module using a light emitting diode (LED) of the conventional art. An LCD backlight module 1 using the LED includes a light source 10, a light guide plate 32, a diffusing plate 34, and a prism sheet 50. The light source 10 is composed of a substrate 12 and a plurality of LEDs 14.
Here, the LEDs 14 are mounted on the substrate 12 in a single row or plural rows and are electrically connected to an external power source.
Meanwhile, the substrate 12 on which the LEDs 14 are mounted is inserted into and fixed to a light source cover 16. A connection groove 16a is formed in a longitudinal direction of the light source cover 16 on its inner surface, so that the substrate 12 can be inserted into and fixed to the connection groove 16a. 
The light guide plate 32 acts to receive light generated from the LEDs 14 of the light source 10 and disperse the light toward the entire top surface.
The diffusing plate 34 is disposed on the light guide plate 32 and acts to uniformly distribute light transmitted through the light guide plate 32.
The prism sheet 50 composed of first and second prism sheets 52 and 54 is disposed on the diffusing plate 34, and induces light from the diffusing plate 34 into a predetermined region (i.e., an image formation region) of the LCD panel. A protective sheet 56 for protecting the prism sheet 50 may be disposed on the prism sheet 50.
Meanwhile, the LED 14 of the conventional LCD backlight module 1 described above is made of point light source shaped LEDs 14. Thus, for an LCD requiring a surface light source for screen display, light emitted from the LEDs 14 must be converted into light of a surface light source through the light guide plate 32.
However, the LEDs 14, being point light sources, do not emit much light at wide angles, but rather emit most of their light at the positions where they are disposed. Thus, a portion of an LED in contact with the light guide plate 32 has bright spots with a hot spot shape and the remaining portions are less bright. This degrades screen brightness distribution uniformity and the overall quality of an image displayed on the screen of the LCD.